The invention relates to a method for operating a motor vehicle.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
The drive device serves for driving the motor vehicle, i.e., for providing a torque that is directed towards driving the motor vehicle. The torque can hereby be either directed towards acceleration or towards deceleration of the motor vehicle, wherein the former results in a positive longitudinal acceleration of the motor vehicle in a forward driving direction of the vehicle, and the latter results in a negative longitudinal acceleration of the motor vehicle in the forward driving direction. The electric drive device can provide the torque for example purely electrically, i.e., solely by means of an electric machine or an electric motor. In this case the motor vehicle can be configured as an electric vehicle.
Beside the electric machine the drive device can of course also have a further drive aggregate, which is preferably of a different type than the electric machine. The further drive aggregate is for example constructed as an internal combustion engine. Correspondingly the drive device is configured as a hybrid drive device, in particular as plug-in hybrid drive device.
The drive device or the motor vehicle can be operated in different operating modes, for example the drive mode, the recuperation mode and the charging mode. In the drive mode electric the electric machine is operated as a motor and the torque that is directed towards acceleration of the motor vehicle is provided or generated by the electric machine. This is accomplished by means of energy withdrawn from the energy storage, in particular exclusively by means of energy withdrawn from the energy storage. As an alternative it is also possible to provide or generate electrical energy for operating the electric machine in a different manner, for example by means of the further drive aggregate, i.e., preferably the internal combustion engine.
In the recuperation mode on the other hand the electric machine is used to charge the energy storage. For this purpose the electric machine is operated as a generator and the torque that is directed toward the deceleration of motor vehicle is provided or produced. In the recuperation mode kinetic energy of the motor vehicle is thus converted into electrical energy and the energy storage is charged with this electrical energy.
From time to time it may be required to charge the energy storage with externally provided electrical energy. This is provided in the charging mode. The charging mode is for example performed during a standstill of the motor vehicle, for example at a stationary charging device. The energy storage is charged until the predetermined target state of charge is reached. Correspondingly the charging mode is performed until this condition is satisfied. The target state of charge can for example be a maximal state of charge of the energy storage, at which the energy storage is maximally charged. The maximal state of charge is for example determined by a manufacturer of the energy storage or the motor vehicle. In the maximal state of charge for example the age of the energy storage can be taken into account, wherein the maximal state of charge for example decreases with increasing age of the energy storage.
It would be desirable and advantageous to provide a method for operating a motor vehicle, which has advantages compared to known methods and in particular enables an efficient use of the electric machine and the electrical energy temporarily stored in the energy storage.